1 Electronic Properties of Nanopore Edges of Ferromagnetic Graphene Nanomeshes at High Carrier Densities under Ionic-Liquid Gating

Copyright © 2014 Taijyu Hashimoto et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In accor-dance of the Creative Commons Attribution License all Copyrights © 2014 are reserved for SCIRP and the owner of the intellectual property Taijyu Hashimoto et al. All Copyright © 2014 are guarded by law and by SCIRP as a guardian. Graphene edges with a zigzag-type atomic structure can theoretically produce spontaneous spin polarization despite being a critical-metal-free material. We have demonstrated this in graphene nanomeshes (GNMs) with honeycomb-like arrays of low-defect hexagonal nanopores by observing room-temperature ferromagnetism and spin-based phenomena arising from the zigzag-pore edges. Here, we apply extremely high electric fields to the ferromagnetic (FM) GNMs using an ionic-liquid gate. A large on/off-ratio for hole current is observed for even small applied ionic-liquid gate voltages (Vig). Observations of the magnetoresistance behavior reveal high carrier densities of ~1013 cm−2 at large Vig values. We find a maximum conductance peak in the high −Vig region and its separation into two peaks upon applying a side-gate (in-plane external) voltage (Vex). It is discussed that localized edge-π band with excess-density electrons induced by Vig and its spin splitting for majority and minority of spins by Vex (half-metallicity model) lead to these phenomena. The results must realize critical-element-free novel spintronic devices